thanks. ill give the voxengo one a try.

it has to be realtime due to the technique i am using.

wash the room with pink noise. get a microphone in the same room and run it through a spectrum analyser. turn up the microphone gain, gradually as the gain rises the modes of the room start to appear.

the difficulty is getting an EQ to knock out the peaking frequencies. as you continue the higher modes start appearing.